Introduction <p>Injections with botulinumtoxinA (BoNTA) are the most common nonsurgical aesthetic procedure but carry risks such as unintended muscle diffusion. Understanding formulation behavior is key to optimizing safety and efficacy.</p> <p>This study compares the diffusion characteristics from letibotulinumtoxinA (Leti-BoNTA) to onabotulinumtoxinA (Ona-BoNTA) and abobotulinumtoxinA (Abo-BoNTA) and its impact on muscle relaxation of frontalis muscle.</p> Methods <p>In a double-blind, randomized trial, 30 healthy adults received Leti-BoNTA on one forehead side and either Ona-BoNTA or Abo-BoNTA on the other. Anhidrosis was measured via Minor’s starch test over 6&#xa0;months, and wrinkle severity was assessed using standardized photography and the Croma Scale.</p> Results <p>Leti-BoNTA had a significantly smaller maximal anhidrotic area than Ona-BoNTA (−15.1 ± 5.5 cm², p &lt; 0.001) and Abo-BoNTA (-25.2 ± 14.5 cm², <i>p</i> &lt; 0.001). An area under the curve (AUC) analysis confirmed the largest area of anhidrosis for Abo-BONTA over the 6-month period, followed by Ona-BONTA and Leti-BoNTA. Despite its lower diffusion, Leti-BoNTA effectively improved wrinkles, with ≥ 1-point improvement in 92% of subjects by week 2.</p> Conclusions <p>Leti-BoNTA provides wrinkle reduction with a more limited diffusion, as assessed with the Minor’s starch–iodine test. Its precise action in this trial implies to be a viable option when controlled spread is essential.</p> Clinical Trial Registration <p>The trial EU CT: 2024–511047-26–01 was registered on 23 March 2024.</p>